Zinc compounds have long been used in the treatment of wounds. The bacteria-inhibiting and local-drying properties of zinc are well known. Colophony has also been earlier used for its bacteria-inhibiting properties.
Colophony is obtained from certain Pinus species and consists of about 90% free resin acids, with the remainder consisting of neutral substances, oxidized terpentines and minor quantities of esters and anhydrides, depending upon the origin of the colophony. The resin acids are a group of mono-basic carboxylic acids, all with a phenanthrene skeleton and all having 20 carbon atoms in the molecule. With two exceptions, dextro-pimaric acids, the resin acids exhibit the same substituents in the same positions and differ only with respect to the number and the positions of the double bonds.
It is also known to use zinc compounds in combination with colophony in, for instance, zinc tape intended for wound care. MEZINC.RTM. (from Monlycke AB), which is an occlusive dressing consisting of cotton fabric coated with PVC and an adhesive substance consisting of rubber, mineral oils, colophony and Zn O possesses good bacteria inhibiting properties against various bacterial strains. In this case, zinc compounds and colophony are used for their respective bacteria inhibiting effect and colophony is also used as a mediator for the transportation of zinc ions to tissue and, in the adhesive substance, also for its adhesive properties.
One disadvantage with the use of adhesive products which contain zinc compounds in combination with colophony is that these products engender contact-allergic reactions in many people, which has reduced the use of these adhesive products. It is true that when used, the zinc present in the adhesive product will neutralize or inactivate the major part of the colophony present. The contact allergic reactions remain, however, to a large extent.
It is known from Patent Abstract of Japan, Vol. II, No. 262, C-442, abstract of JP62-63518, publ. 20th Mar. 1987 and Patent Abstract of Japan, Vol. 8, No. 8, C-236, abstract of JP59-67219, publ. 16th Apr. 1984, that substances or products which contain abtic acid or dehydroabietic acid and/or dihydroabietic acid are effective against passive cutaneous anaphylaxis (PCA), which is a rapid hypersensitive reaction (anaphylactic) which manifests itself in hayfever, urticaria, argio neurotic oedema, atopic eczema, anaphylactic shock or skin rashes within a period of about 10 to 20 minutes. This anaphylactic effect shall be held separate from another type of allergic condition with which the present invention is concerned, namely the classic contact eczema which is effectuated through direct contact between immune cells and cells which have the allergen bound to their surfaces and not by humoral antibodies, this reaction developing within about 12 to 48 hours. The two publications cited above are not concerned with contact allergies but alledge an inhibiting effect of the acids against PCA.